JPH03197907A - Method for aligning optical axis position of optical parts - Google Patents

Abstract

PURPOSE:To improve the working efficiency and positioning accuracy at the time of aligning the optical axis positions of two optical parts having planes of polarization by relatively rotating and moving the two optical parts up to the 3rd angle position which is the intermediate of 1st and 2nd angle positions and making the optimum optical axis alignment. CONSTITUTION:A package 51 is rotated by a prescribed angle quantity in either rotating direction (1st direction) by an theta stage 2. The transmitted light output in this angle position (1st angle position) is detected and the package 51 is rotationally driven in an opposite direction (2nd direction). The rotation of the package 51 is stopped where the transmitted light output attains the same value as the value of the light output in the 1st angle position. The angle feed rate beta deg. from the 1st angle position is calculated at this time. The package 51 is then rotationally driven by 1/2beta deg. in the 1st direction. The optical axes of the two optical parts align interpolatively with good accuracy in this way and the two optical parts eventually have the positional relation with which the transmitted light outputs thereof are maximized.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for aligning an optical axis of an optical component, an object of the present invention is to provide an optical axis alignment method that can improve workability and accuracy during optical axis alignment. , for mutually aligning the optical axes of two optical components, at least one of which has a plane of polarization, a transmitted light output detection means capable of detecting the output of light that can be transmitted through both of the optical components, and a relative position between the two optical components. In the optical component optical axis positioning device, the optical axis alignment device has a position adjusting means that can adjust the position, and the optical components are moved in a first direction at relative angles corresponding to the maximum transmitted light output and the minimum transmitted light output, respectively. A relative rotational movement is made to an arbitrary angular position in the middle, the transmitted light output at the first angular position is detected, and the same transmitted light output is detected from the first angular position in a second direction opposite to the first direction. The above-mentioned optical components are relatively rotationally moved to a second angular position where the above-mentioned first angular position and the second angular position are obtained, and the above-mentioned optical components are relatively rotationally moved to a third angular position intermediate the first angular position and the second angular position. The configuration is such that optimal optical axis alignment of both the optical components is obtained.

[Industrial application field]

The present invention provides a transmitted light output detecting means capable of detecting the output of light that can pass through both optical components, and a transmitted light output detection means for mutually aligning the optical axes of two optical components, one of which has a polarization plane. The present invention relates to an optical axis positioning method in an optical axis positioning apparatus for optical components, which has a position adjustment means capable of adjusting the relative positions of both optical components.

[Prior Art] In optical fiber communication systems, as the speed of the system increases, reflection noise generated when reflected light from optical connections etc. re-enters the laser diode (LD) becomes a problem. In order to solve this problem, optical semiconductor modules that include built-in optical isolators that have a non-reciprocal propagation function that can remove reflected and re-incident light are increasing in number. An example of such an optical semiconductor module (LD module) is shown in FIG. 4. In the figure, 51 denotes an LD package (hereinafter referred to as
54 is an optical isolator case (hereinafter simply referred to as a case) in which the optical isolator 55 is built-in;
Reference numeral 56 denotes an adapter into which a ferrule 58 holding an optical fiber 57 is fitted and a second lens 59 for optical coupling is accommodated.

These package 51, case 54, and adapter 5
6, the connection between the package 51 and the case 54, that is, the alignment of the optical axis between the LD chip 52 and the optical isolator 55 will be described below. Currently, the case 54 is set on the package 51, the LD chip 52 emits light, the power of the light transmitted through the optical isolator 55 is detected, and the relative position of the package 51 and the case 54 is adjusted so that the power is maximized. The angle is visually adjusted to obtain the optimum optical axis positional relationship.

[Problem to be Solved by the Invention] However, in the case of an optical component such as an optical isolator that has a plane of polarization, the output of transmitted light depends on the relative angle adjustment amount (displacement) between the LD chip and the optical isolator. On the other hand, it changes as if drawing a sine wave (sine curve) curve.

Therefore, the change in optical output with respect to angular displacement is extremely small near the maximum value of the transmitted output that should be matched, and therefore the conventional adjustment method has good accuracy (the polarization axes of the LD chip and the optical isolator cannot be precisely aligned). It is quite difficult to leave.

In view of these points, it is an object of the present invention to provide an optical axis alignment method that can significantly improve work efficiency and positioning accuracy when aligning the optical axes of two optical components having polarization planes.

[Means to solve the problem]

In order to solve the above problems, according to a method for aligning optical axes of optical components according to the present invention, the method for aligning the optical axes of two optical components, at least one of which has a polarization plane, is performed. In an optical axis alignment device for an optical component, which includes a transmitted light output detection means capable of detecting the output of light that can be transmitted, and a position adjustment means capable of adjusting the relative position of the two optical components, (a) both of the light The component is relatively rotationally moved in a first direction to an arbitrary angular position between the relative angles that can correspond to the maximum transmitted light output and the minimum transmitted light output, respectively, and (0) the transmitted light output at the first angular position is detecting &~ a second direction opposite to the first direction from the first angular position;
(b) relatively rotationally moving the optical components to a second angular position at which the same transmitted light output is obtained in the direction; and (b) to a third angular position intermediate between the first angular position and the second angular position. A structural feature is that both of the optical components are relatively rotationally moved, thereby obtaining optimal optical axis alignment of both of the optical components.

[For production]

The optical component to be aligned with the optical axis is relatively rotationally moved by a predetermined angle in the first direction, the transmitted light output is detected, and from there, the transmitted light output is detected at a second angular position where the same transmitted light output is obtained in the opposite direction. The relative rotational movement is made to a position intermediate between the first and second angular positions. This allows the polarization axes of both optical components to match well.

〔Example〕

The present embodiment will be described below with reference to the drawings.

FIG. 1 is an overall schematic diagram of an embodiment of an optical axis alignment device for optical components according to the present invention. Referring to the figure, one optical component to be aligned with the optical axis, that is, an LD package 51 (LD chip 52), is placed on the center side of the base 1 via a θ stage 2 and a fixture 3 fixed thereon. It is removably fixed. The θ stage 2 is capable of rotating the LD package 51 around its solid axis.

The other optical component to be aligned with the optical axis, that is, the optical isolator case 54 (optical isolator 55) is placed above the package 51. This case 54 includes an X stage 5, a Y stage 6, and
The package 51 can be pressed and brought into close contact with the package 51 by the Z stage 7 via a pressing/adjusting jig 8 connected to the Z stage 7, and can be moved in the in-plane direction of the base 1 by the X stage 5 and Y stage 6. I'm starting to get it.

On the upper side of the package 51 and the case 54, there is a built-in amplifier that can detect the output of light emitted from the LD chip 52 (not shown) and transmitted through the optical isolator 55 (not shown) during optical axis alignment. The detector 10 is connected to the X stage 11 and Y stage 12 arranged on the left side of the base through metal fittings 13.
, 12, it can be moved in the in-plane direction of the base 1.

The control circuit 20 that centrally controls the above mechanical configuration is
For example, a ROM (read only memory) 22 and a RAM (random access memory) configured as a microcomputer and interconnected by a bidirectional bus 21
23, a CPU (microprocessor) 24, an I10 port 25, and an A/D converter 26.

The A/D converter 26 is supplied with an analog voltage electrical signal that can be output from the transmitted light detector 10 described above.

The story goes back and forth, but each of the above stages 2.5.6゜7.1
1 and 12 each have a built-in pulse motor (not shown) as a drive source, and a linear or rotary bearing (
(not shown) so that a predetermined movement can be performed. And the motors of these stages are controlled by the CPU
, a distribution circuit, an excitation circuit, etc., each of which is independently driven and controlled based on commands from the microcomputer 20.

The second section describes the process of actually aligning the optical axes of the package 51 (LD chip 52) and the case 54 (optical isolator 55) using the apparatus of this embodiment having the above configuration.
This will be explained based on the flowchart schematically shown in the figure.
The relationship between the relative angle of and the output of light transmitted through both optical components will be briefly explained. As described above, when the relative angle is plotted on the horizontal axis and the transmitted light output is plotted on the vertical axis, a sinusoidal curve is drawn as shown in FIG. 3. The positional relationship between the two optical components to be optically aligned is when the relative angle θ (displacement) is zero (0), that is, when the transmitted light output P is maximum (P wax).

First, the package 51 is fixed to the fixing jig 3 on the θ stage 2, and then the case 54 is placed on top of it, and the X stage 5
, the Y stage 6, and the Z stage 7 (step 201). At this time, the optical axes of the LD chip 52 and the optical isolator 55 are aligned to some extent (relative angle θ-θ).

: θ. is a value as close to zero as possible) Set the positional relationship.

Further, the light emission output of the LD chip 52 is set to a predetermined amount.

Next, the package 51 is rotated by a predetermined angle α°, for example, 45°, in one of the rotational directions (first direction) by the θ stage 2 (step 203), and the package 51 is rotated at this angular position (first angular position). Detect the transmitted light output P1 at (step 205).

Next, the package 51 is moved in the opposite direction (second direction).
(step 20?), and when the transmitted light output P becomes the same value as the optical output PI at the first angular position, the rotation of the package 510 is stopped (steps 209 and 211). The angular feed amount β° from one angular position (or in practice, the feed pulse amount for driving the motor, etc.) is calculated (step 213).

Next, the package 51 is now rotated by Aβ0 in the opposite direction, that is, in the same first direction as the first direction (step 215), so that, as can be well understood from the characteristic diagram of FIG. By interpolation, the optical axes of both optical components have good precision (-defective, that is, both optical components have their transmitted light output P
This means that the positional relationship is such that (P wax) is the maximum.

As explained above, according to the adjustment method of this embodiment, it is possible to align the optical axes of both optical components mechanically and with high precision, extremely simply and reliably. Specifically, according to this method, the accuracy is 20 to 3 times higher than the conventional method of exploratory adjustment to maximize the transmitted light output (peak).
It is experimentally confirmed that this is improved by 0 times.

Although not mentioned above, after each rotational movement of the package 51, the position of the detector 10 is adjusted in order to correct the angular deviation of the emitted beam, and the relative position of both optical components is adjusted except for the angle. It is preferable to do so.

Further, in the above embodiment, the adjustment is performed fully automatically, but it is also possible to perform the adjustment semi-automatically without using the microcomputer 20. That is, a power meter (not shown) for displaying the output from the detector 10 in analog or digital form, for example, and a device capable of displaying, for example, the amount of movement pulses of the necessary stepping motor, are provided, and these indicated values can be visually checked.・While performing calculations, adjustments can be made according to the flowchart in Figure 2 above.

Furthermore, in the above embodiment, the angle α1 when rotating the package 51 in the first direction (step 203) is set to 45°, for example, but it is not limited to this, and may be any experimentally determined or practical angle. The optimum angle amount may be used.

Needless to say, the essence of the present invention is to focus on a characteristic region where the optical output varies greatly even with a slight angular shift, and to interpolate the polarization axis and number from two angular positions where the same optical output in that region can be detected. Therefore, the idea itself is not limited to the above embodiment. In other words, almost all optical modules that involve polarization (for example, low polarization) The present invention can be applied to alignment of optical axes between fibers, optical coupling between a polarizing prism and an optical fiber, and the like.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily and mechanically perform optical axis positioning work while improving the accuracy thereof, which is extremely practical and economical.

[Brief explanation of drawings]

Fig. 1 is an overall schematic configuration diagram of an embodiment of an optical axis alignment device for optical components according to the present invention, Fig. 2 is a schematic flowchart of optical axis alignment, and Fig. 3 is a diagram of relative angle and transmitted light output. The characteristic diagram, FIG. 4, is a longitudinal sectional view of an example of an optical semiconductor module. 2...θ stage, 10...detector, 2
0...Control circuit, 51°°LD/Cage 52.・-LD chip... 54... Optical isolator case, 55... Optical isolator.

Claims (1)

[Claims] 1. Two optical components (5
1, 52, 54, 55) for mutually aligning the optical axes of the optical components (51, 52, 54, 55); In an optical component optical axis positioning device having a position adjusting means capable of adjusting the relative positions of both optical components, (a) both optical components (51, 52, 54, 55) are placed in a first position.
(b) detect the transmitted light output at the first angular position; c) A second direction opposite to the first direction from the first angular position.
(d) the first angular position and the second angular position; (d) the first angular position and the second angular position; middle third
Both optical parts (51, 52, 54, 55) are moved up to the angular position of
) is relatively rotationally moved, thereby obtaining optimal optical axis alignment of both the optical components (51, 52, 54, 55).